Power and data distribution systems employed in large commercial and industrial operations can be complex and widely divergent in design and operations. Motor control centers (MCCs), for example, are used in these operations to manage both application of electrical power as well as data communication to a variety of loads. Within the MCC are disposed a variety of components or devices used in the operation and control of the loads, such loads typically include various machines or motors. Typically, the MCC is connected to a main power line that feeds 3-phase ac power, such as 208 to 690 Volt ac power, into the MCC. The MCC then manages and distributes this power to various components within the assembly for operation. Exemplary devices contained within the MCC are motor starters, overload relays, and circuit breakers. These devices are then affixed within various “units” within the MCC. Each unit can be assigned a specific task and each unit may also contain devices that correspond to that task. For example, each unit may be assigned various remote control and monitoring operations.
Many of the components within the units, however, run at different electrical levels than provided by the main power lines, i.e. secondary power, typically lower voltage ac, single phase ac or even dc power. Moreover, devices or components within individual units may require a voltage level different than other components. Accordingly, the main power may be split off or transformed down to lower voltage levels as appropriate to the given component, or, alternatively, a completely separate supply source may be provided. For example, one phase of incoming 3-phase power may be used to provide single phase ac power, or a separate lower ac or dc voltage supply may be employed. Subsequently, this secondary power may be distributed to the various components. Additionally, data signals transmitted between the components or from external networks to and from the MCC may also require interconnection. Typically, the transmission of the secondary power and network data is accomplished via a medley of network and power cables.
During the course of operations, components within the MCC may be changed, added or warrant replacement for any number of reasons. In conventional systems, the unit is removed from the MCC to provide a technician access to the components therein. Moreover, the unit is removed prior to servicing so as to positively ensure interruption of the main power supply. Such removal typically is accomplished by completely disengaging the unit from the MCC. Both main and secondary power, as well as data signals, are then no longer transmitted between the MCC and the removed unit or its components. This creates a number of concerns for the technician. Many MCCs or housed components of the MCCs are electrically interconnected in a “daisy chain” manner. Accordingly, removal of one unit within the MCC may bring the entire MCC or any downstream devices off-line. Additionally, problems with components housed within the unit become more difficult for the technician to diagnose because many of the components within the unit become inoperative on removal. The unit would be easier to diagnose if, for example, the main power was disconnected while the distributed secondary power and network data remained coupled. Moreover, problems occurring in the field may be difficult to replicate and diagnose in a separate laboratory environment. That is, the units and components are more reliably tested in their application environment, while main power is disconnected.
There is a need, therefore, for an improved technique for interconnecting components in an electrical system such as MCCs and the like. There is, in particular, a present need for an easily and directly engageable and disengageable connection (i.e. not hard-wired) between the component assembly and the secondary power and network data conductors which is capable of maintaining engagement even when main power is disconnected.